import SwiftUI
import VoiceCatCore

/// The drilled-into view for a single channel: a Join control, the people currently in the
/// channel, and any sub-channels (each drilling deeper via a nested `ChannelDetailView`).
struct ChannelDetailView: View {
    let channel: Channel
    @Bindable var session: SessionState

    @State private var showPasswordPrompt = false
    @State private var password = ""

    private var isCurrent: Bool { session.currentChannelId == channel.id }
    private var people: [User] { session.users.filter { $0.channelId == channel.id } }
    private var subchannels: [Channel] {
        session.channels.filter { $0.parentId == channel.id }.sorted { $0.name < $1.name }
    }

    var body: some View {
        List {
            Section {
                if isCurrent {
                    Label("You're here", systemImage: "checkmark.circle.fill")
                        .foregroundStyle(.green)
                        .accessibilityLabel("You are in this channel")
                } else {
                    Button {
                        join()
                    } label: {
                        Label("Join Channel", systemImage: "arrow.right.circle.fill")
                    }
                    .accessibilityLabel("Join \(channel.name)")
                }
            }

            Section("People") {
                if people.isEmpty {
                    Text("No one here yet.")
                        .foregroundStyle(.secondary)
                } else {
                    ForEach(people) { user in
                        UserRow(user: user, session: session)
                    }
                }
            }

            if !subchannels.isEmpty {
                Section("Channels") {
                    ForEach(subchannels) { sub in
                        NavigationLink {
                            ChannelDetailView(channel: sub, session: session)
                        } label: {
                            ChannelRow(channel: sub, session: session)
                        }
                        .swipeActions(edge: .trailing) {
                            if session.permissions.isAdmin {
                                Button(role: .destructive) {
                                    session.deleteChannel(sub.id)
                                } label: {
                                    Label("Delete", systemImage: "trash")
                                }
                            }
                        }
                    }
                }
            }
        }
        .navigationTitle(channel.name)
        .navigationBarTitleDisplayMode(.inline)
        .alert("Channel Password", isPresented: $showPasswordPrompt) {
            SecureField("Password", text: $password)
                .accessibilityLabel("Channel password")
            Button("Join") {
                session.joinChannel(channel.id, password: password)
                password = ""
            }
            Button("Cancel", role: .cancel) { password = "" }
        }
    }

    private func join() {
        if channel.passwordProtected {
            showPasswordPrompt = true
        } else {
            session.joinChannel(channel.id)
        }
    }
}